Load estimator for scraper

ABSTRACT

A load estimator is disclosed for use with a scraper. The load estimator may have a first sensor configured to generate a first signal indicative of a performance parameter of the scraper, a second sensor configured to generate a second signal indicative of a hydraulic pressure associated with a bowl of the scraper, and a controller in communication with the first and second sensors. The controller may be configured to classify a current segment of an ongoing work cycle based on the first signal. The controller may also be configured to selectively estimate a load of material contained with the bowl of the scraper based on the second signal only when the current segment is classified as a segment where the load can be reliably estimated.

TECHNICAL FIELD

The present disclosure relates to a load estimator and, moreparticularly, to a load estimator for a scraper.

BACKGROUND

A scraper is a mobile construction machine used for transportingmaterial over short distances. The scraper generally consists of atractor that tows a vertically movable hopper known as a bowl over aground surface. A horizontal blade is connected to a leading lower edgeof the bowl such that, when the tractor tows the bowl forward and thebowl is lowered, the horizontal blade cuts into the ground surface andfills the bowl with excavated material. After the bowl is loaded tocapacity, the bowl is raised away from the ground surface and closed atthe leading edge by a vertical blade known as an apron. The scraper thentransports its load to a dump area where the apron is raised and anejector located at a back end of the bowl pushes the load forward out ofthe bowl. The cycle is then repeated until a desired amount of materialhas been moved.

During operation of the scraper, it can be important to keep track ofthe amount of material moved by the scraper. For example, the amount ofmaterial moved by the scraper (i.e., the weight of the material, alsoknown as the payload weight or the load) during each excavation cyclemay be used in determining productivity of the scraper or of aparticular scraper operator. In another example, the payload of thescraper may aid in determining completion of a project, billing of aparticular customer, and/or scheduling of the scraper. Historically, theamount of material moved by a scraper was determined based directly onmeasured pressures of hydraulic rams or cylinders associated with thescraper's bowl. Unfortunately, this method of estimating loading of thescraper was prone to error, as the pressures can fluctuate significantlyduring different operations of the scraper. For example, during loadingwhen the horizontal blade is engaged with the ground surface, fluidpressures within the hydraulic cylinders can be much higher than whenthe blade is away from the ground surface, even though the payload ofthe scraper may not have changed.

One attempt to improve payload estimation of a scraper is disclosed inU.S. Pat. No. 3,154,160 of Rockwell et al. that issued on Oct. 27, 1962(“the '160 patent”). Specifically, the '160 patent discloses a devicefor indicating to an operator the weight of a load carried by a wheeledscraper. The load indicating device is responsive to hydraulic pressurein a load carrying ram of the scraper. The load indicating device isoperative only when front and rear units of the scraper are pivoted totheir raised travel positions and a valve for controlling the ram is ina neutral or hold position. With this configuration, false readings maybe prevented by inhibiting load measuring during engagement of thescraper with a ground surface.

While the load indicating device of the '160 patent may help to improvepayload estimating in some situations, the device may still be less thanoptimal. Specifically, there may be situations where the front and rearunits are not fully raised before travel of the scraper and, in thesesituations, the load indicating device may be inhibited from estimatingthe load. Further, the '160 patent describes no way to calibrate theload indicating device, without which measurement accuracy may degradeover time. In addition, the load indicating device is a purelymechanical device and provides no display flexibility, recordingfunctionality, accumulation tabulation functionality, or communicationability.

The present disclosure is directed to overcoming one or more of theproblems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a load estimatorfor a scraper. The load estimator may include a first sensor configuredto generate a first signal indicative of a performance parameter of thescraper, a second sensor configured to generate a second signalindicative of a hydraulic pressure associated with a bowl of thescraper, and a controller in communication with the first and secondsensors. The controller may be configured to classify a current segmentof an ongoing work cycle based on the first signal. The controller mayalso be configured to selectively estimate a load of material containedwith the bowl of the scraper based on the second signal only when thecurrent segment is a segment wherein the load can be reliably estimated.

In another aspect, the present disclosure is directed to a method ofestimating a load for a scraper. The method may include sensing aperformance parameter of the scraper and sensing a hydraulic pressureassociated with a bowl of the scraper. The method may also includeclassifying a current segment of an ongoing work cycle based on theperformance parameter, and selectively estimating a load of materialcontained within the bowl of the scraper based on the hydraulic pressureonly when the current segment is classified as a segment where the loadcan be reliably estimated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial illustration of an exemplary disclosed machine;

FIG. 2 is a diagrammatic illustration of an exemplary disclosed loadestimator that may be used with the machine of FIG. 1; and

FIG. 3 is a flowchart depicting an exemplary disclosed method ofestimating payload for the machine of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary earth-moving machine 10. Machine 10 maybe a wheeled tractor scraper configured to load material at a firstlocation, transport the material from the first location to a secondlocation, and unload the material at the second location. Althoughcommonly referred to as a “wheeled” tractor scraper, it is contemplatedthat machine 10 may be propelled by way of wheels, continuous tracks,and/or belts, as desired. Machine 10 may include a tractor 12operatively connected to a bowl portion 14 and configured to tow bowlportion 14 across a ground surface 16.

Tractor 12 may include multiple components that interact to power andcontrol operations of bowl portion 14. Specifically, tractor 12 mayinclude a frame 18, a front axle assembly 20, a power source 22, anarticulated hitch assembly 24, and an operator station 26. Frame 18 maybe connected to front axle assembly 20 and configured to support powersource 22. Power source 22 may include, for example, a combustion engine28 that drives front axle assembly 20 via a transmission 30 and/orprovides electrical and hydraulic power to bowl portion 14. Transmission30 may embody an electric transmission, a hydraulic transmission, amechanical transmission, or a hybrid transmission having a reverse gearratio and one or more selectable forward gear ratios. Articulated hitchassembly 24 may connect tractor 12 to bowl portion 14, while allowingsome relative movement between tractor 12 and bowl portion 14 in bothvertical and horizontal directions. Operator station 26 may facilitatecontrol of tractor 12 and bowl portion 14.

Articulated hitch assembly 24 may include a curved main beam 32 having afront end 34 and a back end 36. Front end 34 of beam 32 may be connectedthrough a vertical hinge joint 38 and a horizontal hinge joint 40 toframe 18 such that beam 32 may pivot both in the horizontal directionand in the vertical direction relative to frame 18. A cushion actuator42, for example a hydraulic cylinder, may be associated with horizontalhinge joint 40 to provide for selective isolation of operator station 26from vertical movements of bowl portion 14. Cushion actuator 42,together with horizontal hinge joint 40, may form what is known as acushion hitch 45. Cushion hitch 45 may be hydraulically locked duringsome modes of operations such that beam 32 is inhibited from moving inthe vertical direction relative to frame 18, and unlocked during othermodes of operations to allow beam 32 and bowl portion 14 to float in thevertical direction relative to frame 18.

Back end 36 of beam 32 may be connected to bowl portion 14 via a pair ofarms 46 located at opposing sides of beam 32 (only one side shown inFIG. 1). Each arm 46 may include a first end 48 and a second end 50.First end 48 may be pivotally connected to back end 36 of beam 32 via afirst pin 52, while second end 50 may be connected to bowl portion 14via a second pin 54. A pair of bowl actuators 56, for example hydrauliccylinders, may be connected between beam 32 at back end 36 and bowlportion 14, and configured to selectively raise bowl portion 14 awayfrom ground surface 16 and lower bowl portion 14 toward ground surface16 by retractions and extensions thereof, respectively.

Operator station 26 may include one or more interface devices 58 locatedproximal an operator seat and configured to generate control signalsand/or present displays associated with operation of machine 10. In oneexample, interface device 58 may be used to display informationregarding operation of machine 10, for example payload information, aswill be described in more detail below.

Bowl portion 14 may include a bowl 60 connected to and supported by arear axle assembly 62. During extension and retraction of bowl actuators56, bowl 60 may be caused to pivot in the vertical direction about rearaxle assembly 62 such that a leading or front end 64 of bowl 60 may beraised and lowered relative to ground surface 16. In some embodiments,an additional power source 66 may be contained within bowl portion 14and supported by rear axle assembly 62. In these embodiments, powersource 66 may be operated to drive rear axle assembly 62 and therebypush machine 10 across ground surface 16.

Bowl 60 may be a tool embodied as a generally hollow enclosure having anopening 68 at front end 64. A horizontal blade 70 may be located atfront end 64 and positioned to selectively engage ground surface 16 asfront end 64 is lowered by the extension of bowl actuators 56. In thisconfiguration, an extension length of bowl actuators 56 may affect adepth of blade 70 into ground surface 16 and, in conjunction with atravel speed of machine 10, a rate of material removal from groundsurface 16. Similarly, a pressure of fluid within bowl actuators 56 mayreflect a force generated by a load contained within bowl 60.

In one embodiment, bowl portion 14 may also include an apron 72configured to close off opening 68 of bowl 60. Apron 72 may embody atool member that is pivotally connected to bowl 60 at a first end 74 andfree to move at a second end 76 in a fore/aft machine direction relativeto bowl 60. An apron actuator 78 may be connected to a front side ofapron 72 (i.e., to an outside of apron 72 relative to bowl 60) andconfigured to selectively pull apron 72 forward to pivot from a closedposition to an open position, and push apron 72 backward to pivot fromthe open position to the closed position. In one embodiment, apronactuator 78 may include an arm 80 pivotally connected at a first end 82to beam 32, a rod 84 pivotally connected between a second end 86 of arm80 and the front side of apron 72, and a hydraulic cylinder 88 connectedbetween beam 32 and arm 80. An extension of hydraulic cylinder 88 mayfunction to push second end 86 of arm 80 up away from beam 32, while aretraction of hydraulic cylinder 88 may function to pull second end 86down toward beam 32. The upward movement of second end 86 of arm 80 maypull rod 84 up and cause apron 72 to pivot forward away from bowl 60 andexpose opening 68. The downward movement of second end 86 may push rod84 down and cause apron 72 to pivot backward toward bowl 60 and closeoff opening 68. It should be noted that, in other embodiments, machine10 may be equipped with an elevator (not shown) instead of apron 72. Inthese embodiments, the elevator may function to move material enteringopening 68 of bowl 60 rearward and upward away from opening 68.

Bowl portion 14 may be provided with an ejector 90 configured toselectively push material accumulated within bowl 60 out through opening68 when apron 72 has been pulled up by hydraulic cylinder 88. Ejector 90may include an ejector plate 92, and an ejector cylinder 94 connectedbetween ejector plate 92 and a frame member (not shown) of bowl portion14. Ejector plate 92 may be moved by ejector cylinder 94 from a fullretract position at a back end 95 of bowl 60 (shown in FIG. 1) toward afull dump position at front end 64 of bowl 60. When ejector plate 92 isaway from the full dump position, material may be loaded into bowl 60via opening 68 and/or transported within bowl 60. When ejector plate 92is moved toward the full dump position, material accumulated within bowl60 may be pushed out of opening 68. Ejector cylinder 94 may beselectively provided with and drained of pressurized fluid to causeejector cylinder 94 to retract and extend, thereby moving ejector plate92.

As shown in FIG. 2, bowl actuators 56 may be equipped with one or morepressure sensors 96 configured to sense hydraulic pressures of fluidwithin one or more different chambers of bowl actuators 56 (e.g., apressure sensor 96 disposed within or otherwise fluidly connected toeach pressure chamber of bowl actuators 56) and to generatecorresponding signals. The signals generated by pressure sensors 96 maybe indicative of forces acting on bowl 60. When bowl 60 is engaged withground surface 16, the forces may be generated by bowl actuators 56pushing blade 70 into ground surface 16 and ground surface 16 resistingthe motion. When bowl 60 is away from ground surface 16 (i.e., notengaged with ground surface 16), the forces may be generated by a weightof material captured within bowl 60 (i.e., the payload of machine 10).Values of the signals generated by pressure sensors 96 may be directedto a controller 98.

Controller 98, together with pressure sensor 96 and other components ofmachine 10, may form a load estimator 102 configured to detectperformance parameters of machine 10 and the forces acting on bowl 60,and responsively estimate the weight of material loaded into bowl 60 ofmachine 10 (i.e., the payload of machine 10). The performance parametersdetected by load estimator 102 can include any type of parameterassociated with any one or more components of machine 10 that aredescribed above. In the disclosed embodiment, these components includetransmission 30, cushion hitch 45, apron 72, and ejector 90. It iscontemplated, however, that other components may additionally oralternatively be used in determining the payload of machine 10, ifdesired, for example the elevator described above (not shown).Controller 98 may communicate directly with some or all of thesecomponents and/or indirectly with these components, for example via oneor more sensors 100, to detect the performance parameters. Theperformance parameters may include, among other things, a travel speedand/or location (e.g., GPS location or location relative to designateddig and dump locations) of machine 10, a selected gear ratio oftransmission 30, a condition of cushion hitch 45 (e.g., locked orunlocked status, position, pressure, etc.), a condition of apron 72(e.g., opened, closed, position, pressure, etc.), a condition of ejector90 (e.g., retracted, extended, position, pressure, etc.), a condition ofthe elevator (e.g., position and/or pressure), and/or a condition ofbowl actuators 56 (e.g., position and/or pressure). As will be describedin more detail below, controller 98, based on the signal(s) fromsensor(s) 100, may classify a current segment of an ongoing excavationcycle being performed by machine 10 as one of a plurality of knownsegments. In the disclosed embodiment, the known segments include a digsegment (e.g., a segment during which bowl 60 is being loaded withmaterial), a carry segment (e.g., a segment during which bowl 60 is fullof material, bowl 60 is not engaged with ground surface 16, and machine10 is traveling), a dump segment (e.g., a segment during which bowl 60is actively being emptied of material), and a return segment (e.g., asegment during which bowl 60 is empty of material, bowl 60 is notengaged with ground surface 16, and machine 10 is traveling). It iscontemplated that other classifications may also or alternatively beutilized, if desired. And based on the classification and the signalfrom sensor(s) 96, controller 98 may be configured to selectivelyestimate the load carried by bowl 60.

Controller 98 may include any components or combination of componentsfor monitoring, recording, storing, indexing, processing, conditioning,and/or communicating operational aspects of machine 10 described above.These components may include, for example, a memory, one or more datastorage devices, a central processing unit, or any other components thatmay be used to run an application. Furthermore, although aspects of thepresent disclosure may be described generally as being stored in memory,one skilled in the art will appreciate that these aspects can be storedon or read from types of computer program products or computer-readablemedia, such as computer chips and secondary storage devices, includinghard disks, floppy disks, optical media, CD-ROM, or other forms of RAMor ROM. Controller 98 may execute sequences of computer programinstructions stored on the computer readable media to perform a methodof load estimating that will be explained below.

In some embodiments, controller 98 may communicate information relatingto performance of machine 10 and/or an operator of machine 10 to anoffboard entity. Communication between controller 98 and the offboardentity may be facilitated via a communication device 104 located onboardeach machine 10 (e.g., within operator station 26). This information mayinclude, for example, the load estimated to be carried by machine 10, alinked identity of machine 10, a linked identity of the operator ofmachine 10, a machine location, a cycle count for machine 10, and othersimilar pieces of information. Data messages associated with loadestimator 102 may be sent and received via a direct data link and/or awireless communication link, as desired. The direct data link mayinclude an Ethernet connection, a connected area network (CAN), oranother data link known in the art. The wireless communications mayinclude satellite, cellular, infrared, and any other type of wirelesscommunications that enable communication device 104 to exchangeinformation between controller 98 and the offboard entity.

FIG. 3 illustrates an exemplary method stored as instructions on thecomputer readable medium that are executable by controller 98 to performload estimating for machine 10. FIG. 3 will be discussed in more detailin the following section to further illustrate the disclosed concepts.

INDUSTRIAL APPLICABILITY

The disclosed load estimator may be applicable to any type of scraperthat is configured to dig, transport, and dump material in a knownrepeatable excavation cycle. The disclosed load estimator may providefor accurate and reliable estimating of payloads in an autonomousmanner. Operation of load estimator 102 will now be explained withrespect to FIG. 3.

As shown in FIG. 3, the method may begin by controller 98 measuring oneor more pressures of hydraulic fluid associated with bowl 60 (e.g., thepressures within opposing chambers of bowl actuators 56 and/or cushionactuator 42—Step 300). The pressures may be measured by way of pressuresensors 96. These pressures may then be used by controller 98 toselectively calculate a force acting on the corresponding actuator(s)and the payload of machine 10 (Step 305). Calculation of this force maybe accomplished utilizing well-known equations based on the sensedpressures and known effective hydraulic areas within the correspondingactuator(s). In the disclosed embodiment, the payload may be determinedutilizing a lookup chart, algorithm, and/or equation stored in thememory of controller 98 that directly relates the force (oralternatively the pressure) to a weight value of the load.

Controller 98 may then receive and/or detect any number of differentperformance parameters of machine 10 (Step 310). As described above,these performance parameters may include, among other things, a travelspeed and/or location, a selected gear ratio, a cushion hitch condition,an apron condition, an ejector condition, an elevator condition, a bowlactuator condition, or another condition known in the art. Theparameter(s) may be received directly from the corresponding componentor detected via one or more sensors 100 associated with the component.Although shown as the third step in the flowchart of FIG. 3, it iscontemplated that step 310 may be completed before steps 300 and/or 305,simultaneous with steps 300 and/or 305, and/or continuously throughoutoperation of machine 10, as desired.

Controller 98 may be configured to classify a current operation ofmachine 10 as one of a plurality of known segments of a repeatable andongoing excavation cycle (Step 315). As described above, exemplary knownsegments generally include the dig segment, the carry segment, the dumpsegment, and the return segment. Controller 98 may classify the currentoperation based on any one or more of the performance parametersreceived/detected in step 310 described above.

For example, when ejector 90 is at a full dump position (all the wayforward in bowl 60), bowl 60 of machine 10 may most likely be empty anddumping may have already occurred. Accordingly, when ejector 90 isdetected as being at the full dump position, controller 98 may classifythe current operation as the return segment of the excavation cycle,during which machine 10 is traveling back to a dig location after havingdumped its load. In contrast, when ejector 90 is away from the full dumpposition (i.e., at the full retract position all the way rearward inbowl 60), machine 10 could be loaded and controller 98 may classify thecurrent operation as the carry segment of the excavation cycle, duringwhich machine 10 is traveling away from the dig location after havingacquired its load.

In another example, when cushion hitch 45 is detected as being in thelocked mode of operation, machine 10 could still be digging. In thissituation, controller 98 may classify the current operation as the digsegment. However, when cushion hitch 45 is in the float mode ofoperation, machine 10 is likely to have completed or be in the processof completing the carry segment of the excavation cycle and controller98 may classify the current operation accordingly.

In yet another example, when transmission 30 is in a high-speed gear,machine 10 may be traveling or has traveled above a minimum speed tomove from a dig location to a dump location. In this situation,controller 98 may be configured to classify the current operation as oneof the carry or return segments. In some embodiments, controller 98 mayclassify the current operation based on any combination of these and/orother performance parameters.

After classifying the current operation, controller 98 may determine ifthe classified operation is a particular segment of the excavation cycle(e.g., the carry segment, where the load can be reliably estimated) andrespond accordingly (Step 320). For example, when controller 98determines that the current operation is not classified as the carrysegment (Step 320: NO), control may return to step 300. However, whenthe current operation is classified as the carry segment (Step 320:YES),control may proceed to step 325, where the payload signal (i.e., thecalculation of the instantaneous payload of machine 10) may be processed(e.g., filtered and averaged relative to other calculations performedduring the same segment of the same excavation cycle). This processingmay help to improve accuracy in the payload value.

Controller 98 may then determine if the carry segment has been completed(Step 330). This determination may be made in many different ways. Inthe disclosed embodiment, controller 98 may determine that the carrysegment has been completed by determining that the dump segment has beeninitiated. In other embodiments, however, controller 98 may concludethat the carry segment has been completed based on a travel speed, abowl actuator position, an apron condition, an elevator condition, or inanother manner known in the art. Control may cycle through steps 300-330until controller 98 determines that the carry segment has beencompleted.

When controller 98 determines that the carry segment has been completed(Step 330:YES), the filtered and averaged payload signal may then bereported (Step 335). This reporting may include, among other things,display of a representation of the payload signal within operatorstation 26 via interface device 58. This representation may take anyform known in the art (e.g., a numerical value, a percent of a desiredload, a picture, a bar graph, etc.), and may provide information to theoperator regarding a current load being transported by machine 10, ahighest load transported within a particular time period (e.g., during ashift or a lifetime of machine 10), and/or a running total of materialweight transported within the particular period of time. Controller 98may tabulate the running total by tracking completion of cycles duringthe time period and adding the load estimation for each cycle. Theoperator of machine 10 may then use the information displayed oninterface device 58 to improve operation throughout the time period, todiagnose problems with machine 10, to bill a particular customer, totrack progress in completion of an assigned task, and/or for otherpurposes.

In some embodiments, controller 98 may also be configured to transmitthe payload signal to an offboard entity for further processing. Forexample, the information may be transmitted via communication device 104to a worksite manager located remotely from machine 10. The worksitemanager may then use the information for similar purposes describedabove.

After reporting of the machine payload value, controller 98 may continueto monitor machine operation and determine when the ensuing dump segmenthas been completed (Step 340). Control may cycle through step 340 untilthe dump segment has been completed. Once controller 98 determines thatthe dump segment has been completed, controller 98 may then selectivelyimplement calibration of load estimator 102 (Step 345). It iscontemplated that the calibration procedure may be implemented aftercompletion of every dump segment, after a certain amount of time haselapsed, after a particular amount of material has been moved, aftercompletion of a desired number of excavation cycles, or according toanother strategy known in the art.

The calibration procedure may be implemented after completion of thedump segment (e.g., during the return segment) because bowl 60 should berelatively empty at that point in time and because the motion of bowlactuators 56 should be relatively stable. For example, bowl 60 shouldnot engage ground surface 16 during the return segment and bowlactuators 56 should be stationary. Thus, the pressures of hydraulicfluid within bowl actuators 56 should accurately reflect a known emptyweight of bowl 60 (and other components normally supported by bowlactuators 56). Accordingly, the pressures measured during the returnsegment of the excavation cycle should be relatively consistentthroughout time, and controller 98 may be configured to determineadjustment factors based on any changes in the pressures detectedbetween different return segments. These adjustment factors may then beapplied to future payload estimations to help ensure accuracy of theprocess.

Because load estimator 102 may implement payload estimations during onlya particular segment of the excavation cycle of machine 10, accuracy inthe estimations may be high. Further, because load estimator 102 may usemany different criteria for classifying the current segment, there maybe more opportunity to estimate the payload of machine 10 withoutincurring error in the process. Further, because load estimator 102 maybe capable of calibration during every excavation cycle, accuracy may beensured throughout the useful life of machine 10. Finally, the abilityto display different aspects of machine payload within operator station26 and or at a remote offboard location may improve use of theinformation and productivity of machine 10.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed loadestimator. Other embodiments will be apparent to those skilled in theart from consideration of the specification and practice of thedisclosed load estimator. For example, it is contemplated that fluidpressures associated with cushion hitch 45 could additionally oralternatively be used to determine the payload of machine 10, ifdesired. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A load estimator for a scraper, comprising: afirst sensor configured to generate a first signal indicative of aperformance parameter of the scraper; a second sensor configured togenerate a second signal indicative of a hydraulic pressure associatedwith a bowl of the scraper; and a controller in communication with thefirst and second sensors, the controller being configured to: classify acurrent segment of an ongoing work cycle based on the first signal; andselectively estimate a load of material contained with the bowl of thescraper based on the second signal only when the current segment isclassified as a segment where the load can be reliably estimated.
 2. Theload estimator of claim 1, wherein the performance parameter isassociated with at least one of an ejector condition, a transmissiongear, a ground speed or location, a cushion hitch status, an aproncylinder condition, an elevator condition, and a bowl actuator position.3. The load estimator of claim 1, wherein the second signal isindicative of one or more hydraulic pressures within a cylinderconfigured to raise and lower the bowl.
 4. The load estimator of claim1, wherein the controller is configured to: classify the current segmentas one of dig segment, a carry segment, a dump segment, and a returnsegment; and selectively estimate the load of material contained withthe bowl of the scraper based on the second signal only when the currentsegment is classified as the carry segment.
 5. The load estimator ofclaim 5, wherein the controller is further configured to selectivelyimplement a load estimation calibration procedure only when the currentsegment is classified as the return segment.
 6. The load estimator ofclaim 1, wherein the controller is further configured to: estimate theload of material multiple times during a single segment of a sameexcavation cycle; and generate an average value for the load of materialbased on the load estimated during the multiple times.
 7. The loadestimator of claim 1, further including a communication device locatedonboard the scraper, wherein the controller is further configured totransmit the estimated load offboard the scraper via the communicationdevice.
 8. The load estimator of claim 7, wherein the controller isfurther configured to link an identification of the scraper and anoperator identification to the estimated load.
 9. The load estimator ofclaim 1, further including a display located within an operator stationof the scraper, wherein the controller is further configured to cause arepresentation of the estimated load to be shown on the display.
 10. Theload estimator of claim 9, wherein the controller is further configuredto: track completion of cycles by the scraper based on the first signal;tabulate a running total of material moved by the scraper based on thecompletion of cycles and the load estimated during each cycle; and causea representation of the running total to be shown on the display.
 11. Amethod of estimating a load for a scraper, comprising: sensing aperformance parameter of the scraper; sensing a hydraulic pressureassociated with a bowl of the scraper; classifying a current segment ofan ongoing work cycle based on the performance parameter; andselectively estimating a load of material contained within the bowl ofthe scraper based on the hydraulic pressure only when the currentsegment is classified as a segment where the load can be reliablyestimated.
 12. The method of claim 11, wherein sensing a performanceparameter includes sensing a performance parameter associated with atleast one of an ejector condition, a transmission gear, a ground speed,a cushion hitch status, an apron cylinder condition, an elevatorcondition, and a bowl actuator position.
 13. The method of claim 11,wherein sensing a hydraulic pressure includes sensing one or morehydraulic pressures within a cylinder configured to raise and lower thebowl.
 14. The method of claim 11, wherein: classifying the currentsegment of the ongoing work cycle includes classifying the currentsegment as one of a dig segment, a carry segment, a dump segment, and areturn segment; and selectively estimating the load of materialcontained within the bowl of the scraper includes selectively estimatingthe load of material only when the current segment is classified as thecarry segment.
 15. The method of claim 14, further including selectivelyimplementing a load estimation calibration procedure only when thecurrent segment is classified as the return segment.
 16. The method ofclaim 11, wherein selectively estimating the load of material includes:estimating the load of material multiple times during a single segmentof a same excavation cycle; and generating an average value for the loadof material based on the load estimated during the multiple times. 17.The method of claim 11, further including: linking an identification ofthe scraper and an operator identification to the estimated load; andcommunicating the estimated load offboard the scraper.
 18. The method ofclaim 11, further including displaying a representation of the estimatedload within an operator station of the scraper.
 19. The method of claim18, further including: tracking completion of cycles by the scraperbased on the performance parameter; tabulating a running total ofmaterial moved by the scraper based on the completion of cycles and theload estimated during each cycle; and displaying a representation of therunning total within the operator station.
 20. A scraper, comprising: atractor having a transmission; a bowl having a blade at a front end; anejector located at a back end of the bowl; an apron connected at aleading end of the bowl; at least a first sensor associated with atleast one of the transmission, the ejector, and the apron, the at leasta first sensor configured to generate at least a first signal indicativeof a gear ratio of the transmission, a condition of the bowl, acondition of the ejector, and a condition of the apron; a cylinderconfigured to raise and lower the blade into a work surface; a pressuresensor configured to sense a pressure of the cylinder and generate acorresponding second signal; and a controller in communication with theat least a first sensor and the pressure sensor, the controller beingconfigured to: classify a current segment of an ongoing work cycle asone of a dig segment, a carry segment, a dump segment, and a returnsegment based on the at least a first signal; and selectively estimate aload of material contained with the bowl of the scraper based on thesecond signal only when the current segment is classified as the carrysegment.